In the summer of 1972, I attended the workshop on recreating classic experiments in physics at Barnard College.1 This was developed by Samuel Devons, and it was a defining experience that set me toward a research career involving early physics teaching apparatus. During the course of the workshop, I became curious about the original diffraction gratings developed by Fraunhofer and built a wire diffraction. A short note about the gratings was published in the American Journal of Physics the next year.2

During an icestorm, freezing rain fell on a rapidly rotating toy windmill during very windy conditions. As the water froze on the perimeter of the spinning wheel, it formed unusual icicles radiating outward from the perimeter of the wheel (Fig. 1). These centrifugal icicles are easy to understand from a conceptual standpoint — the freezing water drops are forced outward from the center by the centrifugal force, analogous to the sediment in a centrifuge tube. However, explanations from an inertial perspective prove to be very difficult, especially if one is reminded of the tendency of water drops to follow tangential trajectories when the water breaks away from a spinning wheel (see Fig. 2).

This paper presents experiments to detectinfrared radiation (IR).1 The key materials, which are readily available, are the following:

» A phototransistordetector, whose circuit diagram is shown in Fig. 1. The response of the phototransistor, which extends into the near infrared, is shown in Fig. 2, along with the response of the human eye.

Recently, the PBS program “Frontline”1 examined the history of the development of the sport utility vehicle (SUV) and the efforts to force car makers to design SUVs that are less prone to rollover. The dangers of SUV rollovers were spotlighted in the fall of 2000, when the Ford-Firestone scandal prompted Congress to launch a series of hearings focusing on deaths and injuries related to faulty Firestone tires mounted on Ford Explorers. However, during the same 10-year period in which Ford-Firestone rollover crashes caused some 300 deaths, more than 12,000 people — 40 times as many — died in SUV rollovers unrelated to tire failure.1

This article explores efforts to use simulation software in conjunction with peer instruction techniques toward improving student comprehension of particle interactions in ideal and “real” gases. A series of Interactive Physics™ simulations builds group student inquiry from small-scale ideal gas cases through larger, more realistic particle simulations. The mathematics associated with the simulations is intentionally minimized in order to focus student attention on conceptual understanding. References are made to other efforts in this educational direction, both in terms of rationale and applications. A website is cited in the Notes section containing both movie versions of the simulations, and includes the files available for download by IP users.

I recently returned from two years in East Timor, the world's newest nation. There I worked with teachers to develop the national physics curriculum for middle and high schools, taught at the national university (UNTIL), and trained teachers across the half-island. Here I'll share some of my successes and a few of the activities we developed, especially as related to the local culture and tropical environment.

Many instructors use conceptual analogies between water pipes and electrical circuits, but the isomorphism of related transport equations is not as commonly appreciated. The Laws of Fourier, Ohm, and Poiseuille may all be cast into nearly identical forms for flows of heat, electric charges, and viscous fluids, respectively. Examining such formal similarities may enhance student understanding.

How many dimensions are there? The answer used to be four — three spatial and one time dimension. Maybe it still is, though nowadays we hear that the answer may be more, perhaps many more. Many of our students have heard about this on television or read about it. They want to know more. Why do physicists think we need more than three spatial dimensions? What's the point of it all?

Energy is arguably the central unifying concept in physics. The validity of the principles of energy extends almost without change from “classical” physics through all of modern physics. Even processes that are too complex or too far outside the Newtonian regime to be easily described in terms of forces can be described in an accurate and conceptually transparent manner in terms of energy. Thus, energy is a useful central organizing principle in teaching physics conceptually. Every physical process is an energy transformation of some forms of energy into other forms. “Energy flow diagrams” present these transformations visually and approximately quantitatively.1 Even for complex processes where analysis in terms of force and motion would be out of the question, energy flow diagrams show the physical fundamentals in a meaningful manner. This paper discusses energy flow diagrams for a few simple processes, and proceeds to complex socially significant processes.

The purpose of this article is to present a simple apparatus for demonstrating the Poynting-Robertson (PR) effect, which is of interest in planetary astronomy. Our setup involves linear rather than rotational motion, and only needs the standard air-track apparatus that is commonly used in freshman labs to verify conservation of linear momentum.